I am runnig mine of 9V, works fine.
The CV / vactrol is controlling cut off. I don't see why you can't connect it to dual gang pot and be fine.
I am also only using 1 stage of an op-amp. I built 4 of these (now filters with 1 quad op-amp.

Are you sure this will run off a single 9v supply?
Doesn't it need a voltage divider?

I have this on breadboard and it just doesn't sound right, output is too low, plus the res pot doesn't do a thing.
When I remove ground from pin 4 the output goes way up.
Using a TL081 for now

I don't mean to commit topic necromancy (RISE ONCE AGAIN MUAHAHAHH!!) but since my question is related to this thread - the last inverter VCF cricuit posted - can it be cut down to just HPF/LPF by lets say cut out the bandpass part, or is the bandpass stage necessary to create the lowpass output? Perhaps kill the LP stage and just do a HP/BP combo?

I managed to put togetter a 4049 based vco with adjustable tri/saw (I think) output and have to inverters left for uh.. something like a VCF. Any suggestions?

I like this thread. It's like that old sketch from Saturday Night Live: "active filters - talk amongst yourselves"
For me, filters are one of the easiest ways to sculpt that buzzy, glitchy square wave into something even weirder. And filters are one more opportunity to use LDRs, LFOs, etc. Lots of expression possibilities!_________________"The life of a repo man is always intense."

i'm going to try building a 4069 filter stand-alone. Probably only LP, but maybe HP also. i have a 40106 drone synth that i built a WSG filter into - it sounds fine but i'd like something more versatile and with a sharper cutoff freq. I think i'm going to try breadboarding one off the last one Silesius posted (http://i42.photobucket.com/albums/e340/Silesius/FILTER.png). If it turns out well maybe I'll replace the WSG filter in my 40106.

Seems like the conclusion was to do something along the lines of 10k VR for a input/attenuator and use a 20k VR for R3 for res?

I assume all those cap values are in microfarads? So that's 1nF caps used in with that op amp?_________________As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"

Cultural thing ... in the EU the n prefix seems to be used more ... also in the form of 2n2 for 2.2 nF ... and in the US you'll more often see .001 µF, or indeed just .001._________________Jan
(yawning shifts perceived pitch, making things more interesting)

Well since it hasn't been that long since my last reply on this thread - I'm trying to get back at experimenting with electronics and I wonder if anybody has successfully put together an active resonant RC-ONLY vcf? by RC only I mean only resistors and capacitors, no transistors, op-amps, inverters or any semiconductors of any kind - requirements would be acceptable response, more or less decent resonance, and an acceptable range for resonance and cutoff control. Is it even possible and practical to do something like that?

Well since it hasn't been that long since my last reply on this thread - I'm trying to get back at experimenting with electronics and I wonder if anybody has successfully put together an active resonant RC-ONLY vcf? by RC only I mean only resistors and capacitors, no transistors, op-amps, inverters or any semiconductors of any kind - requirements would be acceptable response, more or less decent resonance, and an acceptable range for resonance and cutoff control. Is it even possible and practical to do something like that?

That wouldn't be an active filter, then. It would be a passive one. i imagine you would have a pretty hard time making a resonant filter with only caps and resistors.

Well since it hasn't been that long since my last reply on this thread - I'm trying to get back at experimenting with electronics and I wonder if anybody has successfully put together an active resonant RC-ONLY vcf? by RC only I mean only resistors and capacitors, no transistors, op-amps, inverters or any semiconductors of any kind - requirements would be acceptable response, more or less decent resonance, and an acceptable range for resonance and cutoff control. Is it even possible and practical to do something like that?

Yes. Not 24 db/octave... but could be tweaked...

What about connecting a small speaker to your output and sticking it into your mouth. You could move your jaw, change the shape of your mouth cavity and vary the hole made by your lips. ***UNVERIFIED*** (may want to test with small headphone speaker, earbuds etc.)

Thats not really practical, talk boxes use a hose to separate the electronic parts and the mouth of the user._________________As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"

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